SPI A1 on large Class A faces
- Long polish cycles and sensitive handling in the mold room
- Flow marks and gate blush show more on mirror surfaces
- Repair and weld zones need full polish restoration
Glossary
What Is an SPI A1 Finish? Injection Molding Explained
SPI A1 is the top gloss band on the SPI chart for mirror like cavity polish.
Glossary
SPI A1 is the highest gloss band on the SPI finish chart
Lens grade housings and mirror like cosmetics reference A1 when polish labor is in scope.
SPI A1 targets near mirror reflection on polished cavity steel. It demands sequential diamond polish and disciplined process control on the press.
A1 is a steel finish target, not a guarantee that every resin will look like glass without gate and vent tuning.
Mixed finish molds can shut off A1 land against textured regions when the drawing calls out per face specs.
Cosmetics
High gloss shows every flow witness
SPI A grade parts reflect polish labor in the mold.
- Lens grade programs need gate and vent planning before steel polish.
- Diamond polish time belongs in tooling scope, not surprise change orders.
- Compare SPI chart spoke when buyers mix A and B grades.
Cost
A1 polish versus A2 high gloss
Moving down one band can save steel hours when cosmetics still pass review.
SPI A2 on the same geometry
- Slightly less mirror character with lower polish labor
- Still shows defects if gate location is wrong
- Common compromise on visible housings
Go deeper
Where this term connects
Each link is a different angle on the same program, not a duplicate definition.
SPI finish chart
Compare A through D grades.
SPI finish chartHigh gloss polish spoke
RFQ notes for mirror programs.
High gloss polish spokeSPI A2 finish
One step down on the gloss ladder.
SPI A2 finishEDM
Recast must be removed before A1 polish.
EDMVisual reference
Photos from molding and tooling programs
Images are selected from the NetProto Forge media library for this topic.
High gloss plastic lens or cover
High gloss plastic lens or cover
Reflective molded cosmetic surface
Reflective molded cosmetic surface
Quality check under light on molded part
Quality check under light on molded part
FAQ
SPI A1 questions
Does A1 apply to the plastic part or the mold?
It describes mold steel finish that transfers to the part surface.
Can A1 hide weld lines?
Gloss can highlight flow marks. Gate and fill strategy still dominate.
Where is the full SPI chart?
See the SPI surface finish spoke for A1 through D3 context.
Next step
Match finish spec to CAD
Upload models with Class A faces marked before texture and polish scope is quoted.